This application claims priority of Korea patent Application No. 10-2000-0053928, filed on Sep. 14, 2000.
(a) Field of the Invention
The present invention relates to a free link system for precise control. More particularly, the present invention relates to a free link system for precise control in which by uniformly guiding the motion of links through the use of a link guide system that ascends and descends when raising or lowering a light or heavy object, movement of the object placed on a platform is prevented such that the optimal application of a press panel automatic loading system provided in automatic conveying equipment is realized.
(b) Description of the Related Art
FIG. 1 shows a schematic view of a conventional free link system, FIG. 2 shows an end view of FIG. 1, FIG. 3 shows a view taken along line Axe2x80x94A of FIG. 2, and FIG. 4 shows a view taken along line Bxe2x80x94B of FIG. 2.
A conventional free link system 2 includes a main platform 4, a base 6, a drive assembly 8, and a guide assembly 10. The main platform 4 is a rectangular plate and includes first hinge brackets 12 (for use by the guide assembly 10), which are mounted to each corner area of an inner surface of the main platform 4. Further, second hinge brackets 14 (for use by the drive assembly 8) are provided between the first hinge brackets 12.
The base 6 is rectangular and has outer dimensions that substantially correspond to outer dimensions of the main platform 4. The base 6 and the main platform 4 are provided opposing one another. The base 6 includes third and fourth hinge brackets 16 and 18, which are mounted to an inner surface of the base 6 at positions opposing the first and second hinge brackets 12 and 14, respectively.
The drive assembly 8 includes first drive links 20 having a first end connected to the fourth hinge brackets 18 of the base 6; piston links 28 having a first end connected to second ends of the first drive links 20 via drive link hinge pins 22, and a second end rotatably connected to cylinder brackets 26, the cylinder brackets 26 being connected to hydraulic power-generating cylinders 24; and second drive links 31 having a first end connected to a predetermined position of the first drive links 20 through hinge pins 30, and a second end connected to the second hinge brackets 14 of the main platform 4. The drive assembly 8 is provided substantially along an imaginary longitudinal centerline of the base 6.
The guide assembly 10 includes first free links 32 and second free links 40. The first free links 32 are provided to both sides of the drive assembly 8. First ends of first free links 32 are mounted through a hinge connection to the third hinge brackets 16 of the base 6. Second ends of the first free links 32 are mounted through hinges 34 to a predetermined location of the second free links 40. Rollers 38 are mounted to first ends of the second free links 40 and the rollers 38 are positioned in a guide slot 42 defined by a roller guide 36. Accordingly, the first ends of the second free links 40 are free to move along the roller guide 36. Second ends of the second free links 40 are mounted through a hinge connection to the first hinge brackets 12 of the main platform 4.
With the free link system 2 structured as in the above, if each piston link 28 of the drive assembly 8 is extended by the operation of the hydraulic power-generating cylinders 24, the second ends of the first drive links 20 rise such that the second drive links 31 are displaced. Accordingly, the main platform 4 ascends.
At the same time, the first ends of the second free links 40 of the guide assembly 10 move along the guide slot 42 of the roller guide 36 on the rollers 38. As a result, the second free links 40 are raised. The first free links 32 of the guide assembly 10 are also raised through the interconnection of the second free links 40 and the first free links 32 via the hinges 34, and through the pivoting action of the first free links 32 on the third hinge brackets 16. As a result of the operation of the guide assembly 10, the main platform 4 remains level as it is raised. The main platform 4 is lowered in the opposite manner in which it is raised. In the case where a left end of the main platform 4 is raised, the main platform 4 is tilted to rise with the first and second hinge brackets 12 and 14 as pivot points.
However, the free link system structured as in the above has many drawbacks as follows:
(1) When the main platform is raised or lowered, the amount of lateral motion from the reference line, which is based on the first, second, third and fourth hinge brackets, is not uniform. Accordingly, it is not possible to establish a reference starting point.
(2) Since the path of the curve of motion based on the first, second, third and fourth hinge brackets is not uniform, position variations caused by left and right movement of the object placed on the system is severe such that the system is not suitable for application to a vehicle system.
(3) In a state where a large object is placed on the system, if shock is generated by an abrupt change in position of the object, a substantial load is given to each link or pins between the links. Accordingly, damage or deformation of the links and hinge pins result.
(4) Left and right slipping of the first and second free links results in wear of the links.
(5) The guide assembly, which includes elements that slide along the roller guide, is not structured to prevent lateral leaning of the main platform, particularly in the case where there is a heavy object placed on the main platform.
(6) The system is not suitable for use in heavy load systems or systems where a reference starting point is desired.
(7) A large device results in a complicated structure. This is particularly true with increasing overall size of the free link system.
The present invention has been made in an effort to solve the above problems.
It is an object of the present invention to provide a free link system for precise control, in which by uniformly guiding the motion of links through the use of a link guide system that ascends and descends when raising or lowering a light or heavy object, movement of the object placed on a platform is prevented such that the optimal application of a press panel automatic loading system provided in automatic conveying equipment is realized.
To achieve the above object, the present invention provides a free link system comprising a drive assembly mounted along an imaginary longitudinal center line of a rectangular base, the drive assembly including two identical units provided on opposing ends of the base; a main platform that is raised and lowered by operation of the drive assembly; and a guide frame mounted to the base extending perpendicularly to the same, the guide frame being provided on one end of the base and acting to guide the movement of the main platform.
According to a feature of the present invention, each unit of the drive assembly comprises a hinge bracket mounted to the base along the imaginary longitudinal line; a piston link, a first end of which is rotatably mounted to the hinge bracket and connected to a hydraulic power-generating cylinder; an angled link having an angled portion shaped at a predetermined angle, a first end mounted to a second hinge bracket, which is fixedly mounted to the base, and a second end connected to a second end of the piston link through a hinge connector; and a support link having a first end connected to the angled portion of the angled link through a first hinge pin and a second end connected to the main platform through a second hinge pin.
According to another feature of the present invention, the main platform comprises a support bracket provided on each end of the main platform to which the support links of the drive assembly are connected; and roller assemblies mounted to corners of one end of the main platform, the roller assemblies sliding within the guide frame.
According to yet another feature of the present invention, slide grooves are formed at a predetermined length in the guide frame, and rollers of the roller assemblies are positioned within the slide grooves to enable rectilinear motion therein by rotating about their axes.
According to still yet another feature of the present invention, a side of the main platform not supported by the guide frame follows a predetermined trace as the main platform is tilted by the drive assembly.